Cystnil 150+550 mg is a combination medication used primarily to prevent and manage kidney stones, especially calcium oxalate and uric acid stones. It contains Potassium Magnesium Citrate, which works by making the urine less acidic and increasing urinary citrate levels, thereby reducing the formation and growth of kidney stones. N-Acetylcysteine (NAC), an antioxidant, helps reduce oxidative stress in the urinary tract and may also aid in breaking down mucus-like substances that can contribute to stone formation. This combination improves urinary health and is often prescribed as part of a broader strategy to prevent recurrent stone formation. Regular use should be guided by a healthcare provider, as electrolyte imbalances and gastrointestinal discomfort can occur.